Control circuit for antenna scan systems



Sept. 20, 1949.

B. E. WATT Filed Aug. 9, 1944 IIEL CEN

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7 f \ARMATURE +24v /r l0 gl5 CENTER SET AMPLITUDE 0F l2 SCAN SET J A- A gmwm Patented Sept. 20, 1949 CONTROL CIRCUIT FOR ANTENNA SCAN SYSTEMS Bob E. Watt, Boston, assignments, to the 9 Claims.

This invention relates to a means for controlling the oscillatory scanning of an antenna through a small sector, the angle of which is made adjustable as well as its center position.

It is an object of this invention to provide a means for causing an antenna or the like to cyclically scan a small sector, with means for adjusting the angle of scan and the point about which the scan occurs.

Other objects and features of the present invention will become apparent upon a careful consideration of the following detailed description when taken together with the accompanying drawings; the figures of which represent preferred embodiments thereof.

Fig. 1 is a circuit diagram of one embodiment of the invention; Fig. 2 is a circuit diagram of another embodiment of the invention, and Fig. 3 is a schematic diagram illustrating the operation of the circuits shown in Figs. 1 and 2.

In accordance with the principles of the invention as illustrated in Figs. 1 and 2, an antenna I8 whose motion it is desired to control is provided, geared to the armature of a suitable drive motor I6 which is capable of rotating the antenna in either direction under control of a reversing switch 15 which is disposed in the armature circuit of the motor and adapted to control the direction of the driving current therethrough. To control the operation of the reversing switch l5, a pentode l3 as shown in Fig. l or a triode I! as shown in Fig. 2 are provided, each having a relay I4 disposed in their plate circuit and arranged to complete the circuit to the reversing switch. Geared to the antenna l8 and adapted to move therewith, is the movable arm of potentiometer ll! which supplies an input voltage to the grid of tube [3 or I! and hence controls the current through the relay [4. The particular circuits shown are adapted to control the elevation of an antenna and hence potentiometer I is marked ALT to indicate altitude control. An azimuth control circuit constructed similarly may be used if desired, or the combination of azimuth and elevation may both be used.

If the antenna I8 is rotating so as to cause potentiometer Ill to increase the potential of the grid of the tube [3 or 11, current will increase through the relay 14 until it attains a predetermined maximum value at which instant the relay will close the circuit of relay I9 to operate reversing switch l to stop the antenna l8 and cause it to start in the opposite direction. This moves the potentiometer I!) to reduce the potential on the grid of the tube which causes the current through Mass, assignor, by mesne United States of America, as represented by the Secretary of the Navy Application August 9, 1944, Serial No. 548,679%

relay M to decrease correspondingly until a predetermined minimum current is reached, at which point the relay I9 and reversing switch l5 are again operated to cause the antenna to start in the opposite direction. The interval of time elapsing between the attaining of the predetermined maximum current and the predetermined minimum current through the relay I4 is dependent on the hysteresis of the relay and determines the angle through which the antenna scans. To center the antenna scan about a desired position, the potentiometer I2 is provided, the movable arm of which is connected to the cathode of the tube l3 or IT. Adjustment of this potentiometer changes in part the bias on the tube and hence the point at which potentiometer It causes the relay Hi to operate and release. For example, if potentiometer I2 were adjusted nearer its positive end, antenna l8 would have to move the arm of potentiometer Id closer to one end of its natural cycle before relay 14 would operate, and vice versa. Potentiometer H which is interposed between the output of potentiometer Hi and the grid of tube I3 or H may be adjusted to control the size of the sector angle scanned by the antenna. The potentiometer II also controls in part the bias on tube 13 or IT and hence the operating portion of the grid voltage plate current curve of the tube. The value of the amplitude potentiometer H is made large (in the order of 20,000 ohms) with respect to the centering potentiometer l2, so that the setting at the antenna potentiometer II! will not cause an appreciable change in the centering position by reason of the amplitude potentiometer drawing current.

Although the circuits shown are operated by direct current, it will be understood that minor changes can be made to make the tube and relay operate on alternating current.

In Fig. 3 is shown a diagram illustrating the operation of the above circuits. The diagonal line (1 represents the voltage obtained from the arm of the potentiometer it with rotation of the r antenna, the vertical lines I) and b represent the maximum angle through which the antenna will scan, while the intersection of the horizontal lines a and c with the diagonal or represents the voltage point at which the relay it releases and operates respectively. Adjustments of the centerin potentiometer l2 raises or lowers the position of the horizontal lines 0 and c" without changing the space between them, while adjustment of the amplitude potentiometer i-l changes the space between the two horizontal lines o and 3 because of reasons hereinbefore stated, thereby changing the angle of antenna scan.

Although I have shown and described only certain and specific embodiments of the invention I am fully aware of the many modifications possible thereof. Therefore, this invention is not to be limited except insofar as is necessitated by the prior art and the spirit of the appended claims.

I claim:

1. A means for causing the armature of a motor to oscillate back and forth through a given arc, comprising a means for generating a linearly rising voltage at a given slope in accordance with the direction of rotation of the armature of said motor, means actuating a relay upon attainment of a predetermined level of said generated voltage, a reversing switch adapted to operate in response to said relay so as to change the direction of current through the armature of said motor thereby causing a reversal in the direction of rotation of said motor With a corresponding reversal in slope of said generated voltage which after the elapse of a short time delay caused by the hysteresis eifect of said relay releases said relay to restore the reversing switch to its original position.

2. A means for causing the armature of a motor to oscillate back and forth through a given arc, comprising a means for generating a linearly rising voltage at a given slope in accordance with the direction of rotation of the armature of said motor, a relay, a vacuum tube having at least one grid to which said generated voltage is applied and said relay disposed in the plate circuit thereof, said tube being so biased as to be driven into conduction upon attainment of a predetermined voltage level by said generated voltage, a reversing switch adapted to operate in response to said relay so as to change the direction of current through the armature of said motor thereby causing a reversal in the direction of rotation of said motor and a corresponding reversal in the slope of said generated voltage which after the elapse of an adjustable time delay caused by the hysteresis efiect of said relay, releases said relay to restore the reversing switch to its original position.

3. Apparatus for causing the direction of rotation of a motor armature to change periodically, comprising means responsive to the rotation of said armature for generating a rising voltage when said armature is rotating in a first direction and a declining voltage when rotating in a second direction, means responsive to said rising voltage upon attainment of a predetermined level thereof for reversing the direction of rotation of said armature thereby causing said first-mentioned means to generate a declining voltage, said second-mentioned means being further responsive to said declining voltage at a predetermined level thereof for changing the direction of rotation from its reversed direction back to its initial direction of rotation.

4. Apparatus for causing the oscillation of a motor armature, comprising means responsive to the rotation of said armature for generating a rising voltage when said armature rotates in a first direction and a declining voltage when said armature rotates in a second direction, an electron tube having at least one grid, a cathode and a plate, means for applying a portion of said generated voltage between said grid and cathode. means for applying a biasing voltage between said grid and cathode in series with said portion or" said generated voltage, a relay in circuit with said plate of said tube and responsive upon the attainment of a first level of voltage between said grid and cathode when said armature rotates in said first direction to reverse the direction of current in said armature, thereby reversing its direction of rotation and causing said generated voltage to decline, said relay being further responsive when said voltage between said grid and cathode falls to a level below said first level to again reverse the direction of current in said motor armature.

5. Apparatus as in claim 4 and means for varying the magnitude of said portion of said generated voltage applied between said grid and said cathode for varying the frequency at which said armature oscillates.

6. Apparatus as in claim 4 and means for varying the magnitude of said biasing voltage, thereby enabling selection of the center position about which said motor armature oscillates.

7. Apparatus for causing the aimature of a motor to change periodically in direction of rotation, comprising a first potentiometer driven by said armature, a second potentiometer, a third potentiometer connected between the variable taps of said first and second potentiometers, means for applying a constant voltage to said first potentiometer, means for applying a constant voltage to said second potentiometer, thereby providing at the variable tap-of said third potentiometer a linearly varying voltage, rising or falling in accordance with the direction of rotation of said armature, an electron tube having at least a grid, cathode, and plate, said linearly varying voltage being applied between said grid and cathode, a relay disposed in circuit with the plate of said tube and being actuated upon the attainment of a predetermined level of potential between said grid and cathode of' said tube, and a reversing switch operative in response to said relay actuation so as to change the direction of current through said armature of said motor, thereby causing the reversal in direction of rotation thereof with a corresponding reversal in the variation of said linearly varying voltage, said relay being further adapted to be deactuated' when said voltage reaches a second predetermined level, said reversing switch thereby returning to its original position, said third potentiometer providing means for varying the rate" at which the direction of rotation of said armature periodically changes, said second potentiometer providing means for causing the armature of a motor to rotate in one direction only, thereby enabling selection of the center position of rotation of said armature.

8. Apparatus for causing the direction Of rotation of a motor armature to change periodically comprising, means for generating a linearly rising voltage at a given slope in accordance with the direction of rotation of said motor armature, a relay, means actuating said relay upon the attainment of a predetermined level by said generated voltage, and a reversing switch adapted to operate in response to said relay for changing the direction of current through said motor armature thereby causing a reversal in the direction of rotation of said motor armature with a corresponding reversal in slope of said generated voltage, said relay being further adapted to be deactuated upon the attainment by said generated voltage of a second predetermined level, said reversng switch thereby returning to its original position.

9. Apparatus for causing the armature of a motor to periodically change its direction of rotation comprising, means for generating a lineariy rising voltage at a given slope in accordance with the direction of rotation of said armature, a relay, a vacuum tube having at least one grid, a plate, and a cathode, said generated voltge being applied to said grid, means for biasing the grid of said tube, said relay being disposed in the plate circuit of said tube and adapted to be actuated upon the attainment of a first predetermined level by said generated voltage, and a reversing switch adapted to operate in response to said relay for changing the direction of current through said armature thereby causing a reversal in the direction of rotation of said armature anda corresponding reversal in the slope of said generated voltage, said relay being further adapted to be 5 deactuated upon the attainment by said generated voltage of a second predetermined level, said reversing switch thereby returning to its original position.

303 E. WATT.

Name Date Wolfson Feb. 9, 1943 Number 

